Reflective electrophoretic displays (EPDs) are used in a number of applications where common emissive display technologies such as liquid crystal displays (LCDs) exhibit limitations. The most popular types of EPDs have two key distinctions compared to the more common continuously refreshed LCDs and organic light emitting diode (OLED) displays, namely that they are that they are reflective (rather than emissive), and can also maintain optical state without any applied electrical drive energy. Combined, these two properties give EPDs an advantage in bright environments for applications that show mostly long-dwell content (e.g., electronic books or so-called eBooks, and price labels or other digital readouts) and benefit from low power consumption.
The most common application for large EPDs is currently electronic book readers, although there are other applications as well, such as electronic signage. The canonical architecture for an EPD e-reader is typically comprised of a system-on-chip (SoC) running a Linux-based operating system (e.g., Android), connecting over WiFi and driving an EPD. One architectural limitation of EPD based e-readers is a consequence of the EPD's physical response to electrical stimuli which necessitates an image update process that is very different from continuously refreshed LCDs. There are two particular implications with respect to this architectural limitation. First, EPDs are generally relatively slow to update; to achieve a pixel transition from a black state to a white state may take 250 milliseconds or more, in contrast to LCDs which often respond within 10's of milliseconds or faster. Second, most EPDs exhibit a memory effect, i.e., once the electrical stimulus is stopped the black/gray/white state of the EPD material or so-called electronic ink is approximately static. The EPD effectively integrates the time-varying electrical stimuli provided by the driving chips and display system to change from a known starting optical state to a desired end optical state. As such, an EPD display is referred to herein as one example of an integrating display.